The 2011 Pacific typhoon season is a current event in which tropical cyclones form in the Western Pacific Ocean. The season will run throughout 2011 with most tropical cyclones forming between May and November. The scope of this article is limited to the Pacific Ocean to the north of the equator between 100th meridian east and the 180th meridian. Within the Northwestern Pacific Ocean, there are two separate agencies who assign names to tropical cyclones which can often result in a cyclone having two names. The Japan Meteorological Agency will name a tropical cyclone should it be judged to have 10-minute sustained wind speeds of at least 65 km/h, (40 mph) anywhere in the basin. Whilst the Philippine Atmospheric, Geophysical and Astronomical Services Administration assigns names to tropical cyclones which move into or form as a tropical depression in their area of responsibility located between 135°E and 115°E and between 5°N-25°N even if the cyclone has had a name assigned to it by the Japan Meteorological Agency. Tropical depressions that are monitored by the United States' Joint Typhoon Warning Center are given a number with a "W" suffix. On average, 27 storms form in this basin every year.
During each season several national meteorological services and scientific agencies forecast how many tropical cyclones, tropical storms, and typhoons will form during a season and/or how many tropical cyclones will affect a particular country.
City University of Hong Kong
Since the 2000 Pacific typhoon season, the Guy Carpenter Asia-Pacific Climate Impact Centre (GCACIC), of the City University of Hong Kong (CityUHK), have issued forecasts of activity for each upcoming typhoon season. On May 4 and July 5, 2011, the GCACIC issued forecasts which predicted the amount of tropical cyclones, tropical storms and typhoons there would be during 2011 as well as for how many tropical cyclones will make landfall on China or pass within 100 km (60 mi) of the Korean Peninsula or Japan.
This season the GCACIC predicted in May that 31 tropical cyclones, 27 tropical storms, and 17 typhoons would either form or move into the North Western Pacific this year. In their July forecast, the GCACIC lowered their prediction for the number of tropical storms developing into a typhoon by one which they blamed on the strength of the India-Burma trough. For Southern China the GCACIC predicted in May that seven tropical cyclones would make landfall, during the year compared to an average of five. They further predicted that five of the cyclones would make landfall on Southern China between May and August, while the other two would landfall between September and December. After two tropical cyclones had made landfall on Southern China during June, the July GCACIC forecast predicted that seven tropical cyclones would make landfall, during the main season between July and December. For the Korean Peninsular and Japan, the GCACIC predicted in May that six tropical cyclones would affect either Japan or the peninsular during the year compared to an average of four, and predicted that there would be an above average amount of landfalls on Japan. After three tropical cyclones affected the region in May and June, the GCACIC predicted that seven tropical cyclones would affect either the Korean Peninsular or Japan during the main part of the season.
Tropical Storm Risk Consortium
Since the 2000 Pacific typhoon season, the Tropical Storm Risk Consortium (TSR) of University College London have issued forecasts of activity for each upcoming typhoon season. Forecasts on the number of tropical storms, typhoons and intense typhoons there would be during 2011 in the Western Pacific were/will be released in March, May, July and August.[nb 1] In their March, May and July forecasts, TSR predicted that the season would see activity close to the average with 28 tropical storms, 18 typhoons and 8 intense typhoons developing during the season.
National meteorological service predictions
On January 17, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) reported that they were expecting between 20 and 22 tropical cyclones to pass through the Philippine area of responsibility during 2011. On March 23 the Hong Kong Observatory (HKO), reported that they had predicted that 6-9 tropical cyclones would affect Hong Kong during the season. On April 26, the Thai Meteorological Department predicted that 2 tropical storms would affect Thailand during 2011. They predicted that 1 would move through Vietnam and affect Upper Thailand, during August or September. While the second tropical storm was expected to move through Southern Thailand during October or November. On June 30, Taiwan's Central Weather Bureau predicted that the 2011 season would be near its normal climatic average of 25.7, and predicted that 22-26 tropical storms, would occur over the Western Pacific during 2011, with 3 to 5 of them affecting Taiwan.
Duration April 1 – April 4
Intensity 55 km/h (35 mph) (10-min) 1004 mbar (hPa; 29.65 inHg)
On April 1, the Japan Meteorological Agency (JMA) and Joint Typhoon Warning Center (JTWC) began monitoring an area of low pressure associated with intermittent convection over the South China Sea, roughly 535 km (335 mi) east-southeast of Ho Chi Minh City, Vietnam. The former of these two agencies immediately declared the system a tropical depression, the first of the 2011 season. Following further development of the system, most notably convective banding around the low-level circulation center, the JTWC issued a Tropical Cyclone Formation Alert on the storm. Early on April 2, the agency followed through with this alert and designated the low as Tropical Depression 01W. However, within hours of this, the depression became devoid of convection as wind shear buffeted the system. This prevented the cyclone from intensifying beyond depression status as it remained nearly stationary. Failing to regain convection by April 3, the depression degenerated into a remnant low and the final advisory from the JTWC was issued. The JMA continued to monitor the system as a tropical depression for another day before issuing their last warning on the system.
On March 30, the JMA began monitoring an area of low pressure located southwest of Yap. By April 2, the system developed a low-level circulation, though convection appeared disorganized. Exhibiting good outflow within a region of weak wind shear, the low was anticipated to develop further over the following several days as it drifted west-northwestward. After briefly stalling early on April 3, the storm turned towards the east. Additionally, the JMA considered the system sufficiently organized to be declared a tropical depression. As the system was located to the west of 135°E, PAGASA began issuing advisories on the depression as well, assigning it the name "Amang". Tracking northeastward, the depression eventually developed enough convection to be declared Tropical Depression 02W by the JTWC on April 4. However, this was expected to be brief as a decaying frontal boundary approached from the west and prompted the system to undergo an extratropical transition. This intensification prompted the National Weather Service (NWS) in Tiyan, Guam to issue a tropical storm warning for the islands of Agrihan, Pagan and Alamagan. Interacting with the front and high wind shear, the system became partially exposed and elongated as it moved over cooler waters. Early on April 6, the JTWC issued their final advisory on the depression as it began to dissipate over open waters. Following degradation of the storm's structure, the NWS discontinued warnings for the Mariana Islands on April 6. The JMA continued to monitor the system for several more hours before ceasing advisories on it as well.
Early of May 4, an area of low pressure formed about 140 km (85 mi) to the west of Palau Island. On that same day, the low pressure starts to strengthen rapidly with improved LLCC, tightly–wrapped shallow convective banding and a well–defined center. On the next day the low pressure starts to move northwest in general direction to the seas east of Philippine Islands. However it remained almost stationary by afternoon due to the influence of high pressure that located in the northeast of the system. By that time, its LLCC starts to become elongated and the system was also located in favorable sea surface temperatures with low vertical wind shear. Later of that day, its LLCC starts to consolidate again and the system starts to move northwest slowly, whilst the Japan Meteorological Agency upgraded the system into a tropical depression In the afternoon of May 6, Joint Typhoon Warning Center upgraded the low pressure into a tropical depression. In the same evening, PAGASA upgraded the low pressure into a tropical depression and assigned its local name 'Bebeng'. In the afternoon of May 7, JMA upgraded the tropical depression to a tropical storm, and assigned the name 'Aere'. During the early morning of May 12, the JMA downgraded Aere to a tropical depression while south of Kyushu Island.
Throughout the Philippines, multiple agencies activated their emergency plans as the storm approached. The Armed Forces of the Philippines, the Philippine National Police, and the Philippine Coast Guard were all placed on standby to deploy to areas struck by Aere once the storm passed. Several ports were affected by the storm, stranding 1,379 passengers by the afternoon of May 7. According to the National Disaster Risk Reduction and Management Council, at least 35 people have been killed and two more are missing as a result of Aere. Agricultural losses are estimated at PHP1.37 billion (US$31.7 million). Widespread flooding and landslides damaged homes, blocked off roads and severed communications. In Catarman, Northern Samar, 377.4 mm (14.86 in) of rain fell in just 24 hours, resulted in significant flash flooding.
On May 19, the JTWC reported that an area of low pressure had persisted about 510 km (320 mi) to the southeast of Yap. As the system moved towards the northwest under the influence of a subtropical ridge of high pressure, it rapidly consolidated in an area of light to moderate vertical windshear. The JMA then started to monitor the system as a tropical depression later that day, before the JTWC designated it as Tropical Depression 04W early on May 20. The JTWC then reported later that day that the depression had intensified into a tropical storm with windspeeds of 65 km/h (40 mph), however it later reported that it had overestimated the windspeeds and consequently lowered the storm's status to a tropical depression, based on observations from Yap island. Late on May 21, both the JMA and the JTWC reported that the depression had now become a tropical storm with the JMA naming it as Songda. Over the next couple of days, the system gradually intensified further while moving northwest into PAGASA's area of responsibility. PAGASA named it as Chedeng. At 1200 UTC on May 24, the JTWC reported that Songda had intensified into a typhoon. 12 hours later the JMA followed suit while the system was located about 800 km (500 mi) to the southeast of Manila in the Philippines. It rapidly intensified into a Category 5 typhoon. Songda did not strike the Philippines directly, but came close enough to cause widespread landslides and flooding, as well as killing one person.
After being downgraded from a 5 to a Category 3, Songda battered Okinawa with high winds and heavy rain, before moving up to mainland Japan, weakening further. In Okinawa, 58 people were injured, 5 severely, and thousands were left without power. The typhoon later battered Miyagi, which was already trying to recover from the 2011 earthquake, killing at least 13.
In the afternoon of May 29, Songda became extratropical south of Shikoku Island.
During the evening of May 31, the JMA upgraded an area of low pressure to a tropical depression. Initially, the tropical depression was located about 400 km (250 miles) south west of Hong Kong. The system did not develop further and was downgraded to an area of low pressure by the JMA on June 2.
On early June 8, an area of low pressure formed about 10 km west of Cebu City, Philippines. As it moved towards the Mindoro Strait the JMA and JTWC began to monitor the system. In the early morning hours of June 9, the Philippines' PAGASA upgraded the system to a tropical depression and reported the storm center to be about 450 km west of Dagupan City in the Philippines. The next day, the JMA and JTWC upgraded the tropical depression into a tropical storm, with the JMA naming it Sarika. During the morning of June 11 the JTWC downgraded Sarika to a tropical depression after making landfall in Shantou, China. The JTWC soon issued their final advisory on Sarika. Sarika made landfall on mainland China with winds of 75 km/h (45 mph). As a result of the storm, 23 people were killed in Xianning, and ten more were declared missing. Damages from Sarika are estimated at $248 million.
Early June 15 an area of low pressure area embedded along the Intertropical Convergence Zone located about 250 km west of Puerto Princesa, Palawan. As is moved towards the South China Sea, both the JMA and the JTWC started monitoring it. During the morning of June 15, the JMA upgraded it into a tropical depression. Due to an anticyclone, the system dissipated during the early morning of June 16
On June 15, the JTWC started to monitor an area of disturbed weather that was located about 1350 km (835 mi), to the southeast of Manila, Philippines. Over the next couple of days the system gradually developed further, before late on June 16, the JMA, JTWC and PAGASA, all reported that the system had developed into a tropical depression, with PAGASA naming it as Egay. Egay continued to develop during June 17 as it moved towards the northeast, and on June 18 the JTWC reported that Egay had intensified into a tropical storm. Late on June 19, the JTWC downgraded Egay to a tropical depression, but they upgraded Egay again to a tropical storm on June 20. Early on June 20, the JTWC downgraded Egay to a tropical depression again. On June 21, the JMA upgraded the system into a tropical storm and named it Haima, with the JTWC following suit on June 22.
During the evening of June 23, the JTWC downgraded Haima to a tropical depression after making landfall in Zhanjiang, Guangdong, China but upgraded it to a tropical storm again on June 24. Early on June 25, Haima became a tropical depression after moving inland in Vietnam. As it made landfall over Hanoi, Vietnam, the JTWC and the Hong Kong Observatory downgraded Haima to a low pressure area.
Early on June 20, and area of low pressure about 760 km (470 miles), east of the Philippines began to be monitored by both the JTWC and JMA. That evening, the JTWC issued a Tropical Cyclone Formation Alert. Soon afterwards, PAGASA upgraded the system into a tropical depression, naming it as "Falcon". At the time of the upgrade, Falcon was located about 1000 km (620 miles), east northeast of Cebu City. During the evening of June 21, the JTWC also reported that Falcon had strengthened into a tropical depression. On June 22, both the JTWC and the JMA upgraded Falcon into a tropical storm, and the JMA named it Meari. Meari leaves Philippines with 2 deaths and 5 missing. In the afternoon on June 24, the JMA upgraded Meari to a severe tropical storm as it passed Okinawa, Japan.
On June 26, Meari rapidly moved to the Yellow Sea but slowly passed Weihai, Shandong, China, and then the JMA downgraded Meari to a tropical storm on the same day. On June 27, the JTWC downgraded Meari to a tropical depression before it made landfall in North Korea, and the JMA reported that Meari became a low pressure area later.
Late July 9 an area of low pressure area formed about 300 km (186 mi) east of Aurora as it moves Northwest it has been located 500 km east-southeast of Basco, Batanes.[clarification needed] On the morning of July 9, JMA upgraded the low pressure area into a tropical depression and it was located 450 km northeast of Cagayan. In the afternoon, PAGASA upgraded the low pressure area into a tropical depression and named it Goring. After moving to Fujian, China, it dissipated on the evening on July 10.
On July 11, both the JMA and JTWC upgraded a tropical disturbance to a tropical depression which was located near Minamitorishima. On July 12, both the JMA and JTWC upgraded the system to a tropical storm and named it Ma-on. Early on July 13, the JMA upgraded Ma-on to a severe tropical storm. Late on July 13, both the JMA and the JTWC upgraded Ma-on to a typhoon. After absorbing Tokage, Ma-on reached its peak strength on July 16. The PAGASA named it Ineng on July 17.
As Ma-on was affecting Japan, the JTWC downgraded it to a tropical storm in the evening on July 19. Ma-on made landfall in Tokushima later. The JMA downgraded Ma-on to a severe tropical storm after it made landfall in Wakayama early on July 20. The JTWC downgraded Ma-on to a tropical depression on July 21 and discontinued advisories the following day. The JMA downgraded Ma-on to a tropical storm early on July 23. On July 24, Ma-on weakened into an extratropical cyclone east of the Tōhoku region.
A low pressure area has formed about 740 km north-northwest of Palau. Early on July 14, the JMA upgraded it into a tropical depression, and the JTWC issued a Tropical Cyclone Formation Alert. On July 15, the JMA upgraded the system to a tropical storm and named it Tokage, and the JTWC upgraded it to a tropical depression later. PAGASA also upgraded it to a tropical depression and named it Hanna. Due to the Fujiwhara effect, Typhoon Ma-on, the powerful storm just northeast of Tokage, later weakened Tokage to a tropical depression and completely absorbed it early on July 16.
Originally a low pressure area, the JMA reported that a tropical depression formed from it inland in Guangdong, China on July 16. On July 17, the depression has dissipated.
Originally a low pressure area, the JMA reported that a tropical depression formed from it in the Gulf of Tonkin near Guangdong, China on July 16. However, it quickly dissipated after only six hours.
Early on July 22, an area of low pressure formed to the east of Philippines. The system gradually drifted west over the next few days and late on July 24, the Joint Typhoon Warning Center Started Monitoring the system as a Tropical Depression. Early the next day, the Japan Meteorological Agency (JMA) upgraded the area of low pressure into a Tropical Depression. A few hours later, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) started monitoring the system as a Tropical Depression and named it 'Juaning'. The system continued to drift westwards and strengthened rapidly, that on midnight, that day, the JMA furhter upgraded the system into a Tropical Storm, naming it Nock-Ten. Early on July 27, the JMA reported that Nock-ten continued to strengthen and upgraded it into a Severe Tropical Storm. A few hours later, the JTWC reported that Nock-ten rapidly intensified to a category 1 typhoon and made its landfall over northern Aurora (province) and started weakening. Later the same day, the JMA reported that Nock-ten has exited the Luzon island at Candon maintaining severe tropical storm strength.
Per latest information, the provinces of Albay and Camarines are reported to be completely flooded by the rain. So far, Minor damage to rice crops was reported. More heavier rains are expected throughout the day as the system has exited land into south china sea and will soon start reintensifying. The number of missing was also pushed up to 31 after 22 crewmembers of a fishing boat were reported missing when their fishing boat was caught in the storm off Masbate. Nock-ten suspended all classes in Luzon from Pre-school to college levels on July 26 and 27. In Northern Luzon, Nock-ten poured down heavy rainfall becoming widespread flooding in the area. The national roads were impassable and landslides were also reported. About 26 domestic flights were cancelled from July 26 to 27 due to heavy rains ang strong winds.  The death toll is now upgraded to 27 and more than 60 people are now listed as missing. The National Disaster Risk Reduction and Management Council began rescuing stranded people and searching for fishermen who were lost in the storm.
Late on July 25, the JTWC upgraded the low pressure area to a tropical depression south of Guam. Early on July 26, the JMA also upgraded it to a tropical depression.
Within the Northwestern Pacific Ocean, there are two separate agencies who assign names to tropical cyclones which often results in a cyclone having two names. The Japan Meteorological Agency names tropical cyclones should they be judged to have 10-minute sustained windspeeds of 65 km/h, (40 mph), to the north of the equator between the 180° and 100°E. Whilst the Philippine Atmospheric, Geophysical and Astronomical Services Administration assigns names to tropical cyclones which move into or form as a tropical depression in their area of responsibility located between 135°E and 115°E and between 5°N-25°N even if the cyclone has had a name assigned to it by the Japan Meteorological Agency.
See also: Lists of tropical cyclone names and Tropical cyclone naming
Tropical Cyclones are named from the following lists by the Regional Specialized Meteorological Centre in Tokyo, Japan, once they reach tropical storm strength. Names are contributed by members of the ESCAP/WMO Typhoon Committee. Each of the 14 nations or territories submitted 10 names, which are used in alphabetical order, by the English name of the country. The next 24 names on the naming list are listed here.
The Philippine Atmospheric, Geophysical and Astronomical Services Administration uses its own naming scheme for tropical cyclones in their area of responsibility. PAGASA assigns names to tropical depressions that form within their area of responsibility and any tropical cyclone that might move into their area of responsibility. Should the list of names for a given year prove to be insufficient, names are taken from an auxiliary list, the first 10 of which are published each year before the season starts.
See also: List of retired Pacific typhoon names (JMA) and List of retired Philippine typhoon names
On May 16, 2011, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) announced that the name Bebeng would be retired due to extensive damage and loss of life.
This table lists all the storms that developed in the western Pacific Ocean to the west of the International Date Line during the 2011 season. It includes their intensity, duration, name, landfalls, deaths, and damages. All damage figures are in 2011 USD. Damages and deaths from a storm include when the storm was a precursor wave or extratropical low.
Name↓ Dates active↓ Storm category
at peak intensity↓ Peak 10-min
sustained winds↓ Pressure
hPa↓ Areas affected↓ Damage
(USD)↓ Deaths↓ References
01W April 1 – 4 Tropical Depression 55 km/h (35 mph) 1004 hPa (29.65 inHg) None None None
02W (Amang) April 3 – 6 Tropical Depression 55 km/h (35 mph) 1000 hPa (29.53 inHg) Northern Mariana Islands None None
Aere (Bebeng) May 5 – 12 Tropical Storm 75 km/h (45 mph) 992 hPa (29.29 inHg) Philippines, Japan $31.7 million 44 
Songda (Chedeng) May 19 – 29 Typhoon 205 km/h (125 mph) 920 hPa (27.17 inHg) Philippines, Japan $2.97 million 17 
Tropical Depression May 31 – June 2 Tropical Depression Unknown 1004 hPa (29.65 inHg) None None None
Sarika (Dodong) June 8 – 11 Tropical Storm 75 km/h (45 mph) 996 hPa (29.42 inHg) Philippines, China $248 million 29 
Tropical Depression June 15 – 16 Tropical Depression Unknown 1004 hPa (29.65 inHg) None None None
Haima (Egay) June 16 – 25 Tropical Storm 75 km/h (45 mph) 985 hPa (29.09 inHg) Philippines, China, Vietnam, Laos $16.7 million 18 
Meari (Falcon) June 20 – 27 Severe Tropical Storm 110 km/h (70 mph) 970 hPa (28.64 inHg) Philippines, Japan, China, South Korea, North Korea $1.24 million 11 
Goring July 9 – 10 Tropical Depression 55 km/h (35 mph) 1000 hPa (29.53 inHg) Japan, Taiwan None None
Ma-on (Ineng) July 11 – 24 Typhoon 175 km/h (110 mph) 935 hPa (27.61 inHg) Northern Mariana Islands, Japan $27.8 million 5 
Tokage (Hanna) July 14 – 16 Tropical Storm 65 km/h (40 mph) 1000 hPa (29.53 inHg) None None None
Tropical Depression July 16 – 17 Tropical Depression Unknown 998 hPa (29.47 inHg) China None None
Tropical Depression July 16 Tropical Depression Unknown 1002 hPa (29.59 inHg) China None None
Nock-ten (Juaning) July 24 – still active Severe Tropical Storm 95 km/h (60 mph) 985 hPa (29.09 inHg) Philippines None 27 
11W July 25 – still active Tropical Depression 55 km/h (35 mph) 1004 hPa (29.65 inHg) None None None
Total Depressions: 16 April 1 – Still active 195 km/h (120 mph) 920 hPa (27.17 inHg) $328 million 137